1. Field of the Invention
The invention relates to an apparatus for effecting the sighting of a rifle to accurately align the sights provided on the rifle with the normal eye position of the user when firing the rifle, and particularly to a mechanism for eliminating the effects of trigger jerking on the accuracy of the sighting.
2. Description of the Related Art
A necessary step in the utilization of any new rifle by its purchaser is to adjust the sights of the rifle, particularly the rear sights thereof, to permit the accurate firing of the rifle by its new user. As is well known, the physical contour ii and dimensional location of the eyes of individuals vary substantially, so it is quite important that the rifle be sighted in by the particular user. Resighting is also required if any change in ammunition is effected.
Such sighting is generally accomplished with the barrel of the rifle resting on a support, such as a rail fence, and the stock of the rifle positioned against a fixed support adjacent the shoulder of the user in substantially the same position that the user would expect to assume during all subsequent firing of the rifle. The precaution of resting the barrel and stock of the rifle on fixed supports does not, however, eliminate the adverse effects of an improper trigger squeeze or jerking of the trigger. This is the most common fault encountered not only in the firing of the rifle, but also in the sighting of it, and a jerking of the trigger, however slight, will disturb the accuracy of the sighting. There is a need, therefore, for an apparatus which will permit the sighting of the rifle to be accomplished without utilization of the user""s finger to depress the trigger.
In accordance with this invention, a trigger operating apparatus is provided which is clampable on the rifle by two plates respectively positioned on opposite sides of the trigger guard commonly found on every rifle. In one embodiment of the present invention, a spacer block is secured to one of the plates, disposed within the trigger guard and abutting the forward portion of the trigger guard. The spacer block receives one or more clamping bolts which traverse the other plate. A shaft is rotatably mounted in one of the plates and has an inner end portion lying within the trigger guard and adjacent to the trigger in its unfired position. The outer end of the shaft projects exteriorly of the mounting plate and mounts a manually graspable knob. On the inwardly projecting portion of the shaft, a cam is formed which, by rotation of the shaft, engages the trigger and depresses the trigger to its firing position. Preferably, the shaft is slowly rotated by the user of the rifle and the trigger is cammed rearwardly with a substantially continuous motion. Even if the shaft is rotated at a higher than recommended speed, no jerking of the trigger will result because the cam action moves the trigger smoothly from its inactive position to its firing position.
In another embodiment of the present invention, a trigger operating apparatus is provided which is clampable on the rifle by two plates designed for use by either a right-handed or left-handed user. Those plates are respectively positioned on opposite sides of the trigger guard. The one plate has a recessed area on its periphery to engage the interior surfaces of the trigger guard on either the right or left side. The two mounting plates are secured together by one or more clamping bolts. A cam mounting shaft traverses the mounting plates and extends outwardly from one of the mounting plates for mounting of a manually graspable knob. A rotary cam is secured to the shaft for co-rotation in a selected direction, which rotation is opposed and limited by a helical spring mounted between the cam and the one mounting plate. Preferably, the right-handed user will slowly rotate, either clockwise or counter-clockwise, depending on the cam design, the manual knob which is on the right side of the trigger guard, thereby camming the trigger rearwardly with a substantially continuous motion. For left-handed firing, the mounting plates are reversed in position and the manually operable knob is on the left side of the trigger guard. The cam operation, however, is the same as in the right-handed configuration. Thus, accurate sighting for either a right-handed or left-handed user of the rifle may be accomplished by the elimination of trigger jerking.
In yet another embodiment of the present invention, a trigger operating apparatus with a lock and key feature is secured on the rifle by two clampable plates respectively positioned on opposite sides of the trigger guard. A shaft is rotatably mounted in one of the clampable plates, and an inner end portion of the shaft lies within the trigger guard and adjacent to the trigger in its unfired position. The outer end of the shaft projects exteriorly of the mounting plate and passes through a spring keeper cylinder and is positioned inside a key housing. A bolt aligns the key housing with the spring keeper cylinder. The key housing, which is fitted with the shaft and spring keeper cylinder, is secured to the mounting plate with housing retainer screws. Preferably, the shaft is slowly rotated and the trigger is cammed rearwardly by inserting a key into the key housing and turning with substantially continuous motion. Even if the shaft is rotated at a higher than recommended speed, no jerking of the trigger will result since the cam action moves the trigger smoothly from its inactive position to its firing position.
Still another embodiment of this invention comprises a mounting plate with one or more plug portions extending from the mounting plate. A shaft is rotatably mounted in the mounting plate and a cam is attached to the shaft for engagement with the trigger as in the above-described embodiments, and the apparatus is secured to the trigger guard by pressing the plug portions into the trigger guard. Alternatively, a mounting plate having one or more clamping plates extending therefrom may be used to mount the apparatus to the trigger guard.
Further objects and advantages of the present invention will be readily apparent to those skilled in the art from the following detailed description taken in conjunction with the annexed sheets of drawings, which illustrate several preferred embodiments of the invention.